Having Covid before being vaccinated may end in less immunity

Individuals who caught Covid-19 before they were vaccinated had a weaker immune response to the shots than those that never had the virus, potentially leaving them less protected against reinfection, latest research shows.

Co-funded by the National Institutes of Health, the study released Monday challenges older research that suggested a previous Covid infection enhanced a vaccinated individual’s immune response — a phenomenon referred to as hybrid immunity, which some scientists imagine provides the very best protection against reinfection.

Within the study, researchers from Stanford University analyzed how immune cells present in the blood called CD4+ T cells and CD8+ T cells reply to Covid infection and vaccination. Those cells work together to provide an immune response that can assist fend off the virus, killing other cells which were infected. 

The study found that vaccinating individuals who had never been infected with Covid before produced “robust” CD4+ and CD8+ T cell responses to the virus. Vaccination in those people also generated cell-signaling molecules that recruit other immune cells to assist fight Covid, they said. In contrast, researchers said vaccinating individuals with prior Covid infections produced “considerably lower” cell responses “with less functionality.” 

Unvaccinated individuals who caught Covid had even lower levels of CD8+ T cells, they added. 

The researchers said the findings suggest a Covid infection damages a very important immune cell response that’s crucial to fighting the virus, which could leave vaccinated individuals with a previous infection less protected. 

“The apparent damage of the CD8+ T cell response by viral infection is cause for concern, and will leave even vaccinated individuals with a previous infection in danger for subsequent infections or other health issues,” study authors wrote. In addition they said the findings highlight the necessity to develop latest vaccine strategies that may specifically boost CD8+ T cell responses in people previously infected with Covid.

Dr. Stuart Ray, a professor of drugs at Johns Hopkins University, said the study is surprising because it challenges what is understood about hybrid immunity. But he added that “we’ve to be cautious anytime we’re surprised by something.” 

Ray said the findings may stem from the way in which the study was designed, specifically pointing to how researchers examined immune cells within the blood, not the tissue. 

“The cells within the blood will not be an absolute measure of all the pieces within the body. The cells we all know protect us are also in our tissues fighting infections,” he told CNBC. “It’s like if you’re on the lookout for something under the lamppost when it’s over the sphere nearby. You may not be all of the cells we care about.” 

Ray said the study, while interesting, must consider long-term knowledge about how Covid immunity works: “It’s probably not the last chapter on this story.”

The study comes as researchers proceed to research Covid’s impact on individuals even after they get better from the virus, which has infected greater than 100 million people within the U.S. alone because the outset of the pandemic. The nation continues to see nearly 150,000 latest cases each week, in accordance with the Centers for Disease Control and Prevention. 

The brand new research also comes as public health officials consider latest approaches to Covid vaccination that would decrease the variety of doses people need per 12 months or require drugmakers to periodically update their shots to focus on emerging variants of the virus. 

Roughly 81% of the U.S. population is vaccinated with no less than one Covid shot, while nearly 70% have accomplished their primary series doses, in accordance with the Centers for Disease Control and Prevention.